System Messages

The following VNAV system messages that may be displayed in the messages window at the bottom of the display.

Table 56: VNAV System Messages

VNAV System Message

Comments

UNABLE VNAV

Excessive cross-track error.

The current cross-track exceeds the limit, causing VNAV to be temporarily unavailable.

UNABLE VNAV

Excessive track angle error.

The current track angle error exceeds the limit, causing VNAV to be temporarily unavailable.

UNABLE VNAV

Parallel course selected.

VNAV is not available while a parallel course is active.

UNABLE VNAV

Reverted to PIT.

This message is displayed when PATH has reverted to Pitch Hold Mode. This would happen because of an overspeed condition, a vertical discontinuity, or invalid vertical deviation.

ARM VNAV DESCENT

Reset altitude preselect to arm descent.

The flight plan calls for a descent, but the Selected Altitude needs to be reset. No change in altitude can be made unless allowed by the Selected Altitude.

ARM VNAV CLIMB

Reset altitude preselect to arm climb.

The flight plan calls for a climb, but the Selected Altitude needs to be reset. No change in altitude can be made unless allowed by the Selected Altitude.

DISABLE GS TO ARM CLIMB

Press NAV button to enable VNAV track change.

While the GS (glideslope) vertical mode is armed, the flight director will not arm a climb mode. GS must be removed before VNAV can arm a climb mode.

DISABLE GP TO ARM CLIMB

Press NAV button to enable VNAV track change.

While the GP (glidepath) vertical mode is armed, the flight director will not arm a climb mode. GP must be removed before VNAV can arm a climb mode.

UNABLE VNAV ALTITUDE

Cannot meet VNAV altitude constraint.

Based on the current rate of climb or descent, the next flight plan altitude constraint will be exceeded (VNAV Mode remains active).

190-03123-21 Rev A
July 2026